1. Field of the Invention
The present invention relates to a surgical instrument for cutting and removing body tissue from a body area having a restricted space, and more specifically relates to such an instrument capable of performing joint surgery in body joints such as the knee utilizing surgical viewing probes inserted through punctures into the joint regions, without laying open the joint.
2. Description of the Prior Art
In body joints such as the knee having severely restricted operating space, it is impractical to use a cutter having jaws which must expand in order to open and cut since in many instances the restricted space is insufficient to allow the cutting jaws to open. In response to this limitation, a number of surgical instruments have been developed utilizing cutters which do not open and expand to cut body tissue. U.S. Pat. No. 4,203,444 to Bonnell et al discloses such a cutter. The Bonnell device utilizes an outer tube having a side-facing, axially extending cutting port and an internal rotary blade. A vacuum conduit draws the body tissue to be shaved into the cutting port while the rotary blade is driven in shearing relation to the external tube. The vacuum further draws the cut body tissue through the inner tube and out of the instrument for disposal.
One serious problem encountered with the Bonnell device is in cutting thin, soft fibrous material as is typically found in the knee joint. The rotating blade of the Bonnell device has a tendency to pull and spool such soft fibrous materials. Eventually, such spooling can bind the rotating cutting blade and also clog the aspiration chamber.
A further disadvantage of the Bonnell device is encountered after repeated use of the instrument on dense tough body tissues such as the meniscus tissue in the knee joint. After prolonged use, the rotary cutting blades of the Bonnell device become dulled and the meniscus tissue simply pops out of the cutting port as the rotating cutter blades spin resulting in little or no cutting of the meniscus tissue.